Background

Dandelion is a member of the Asteraceae/Compositae family closely related to chicory. It is a perennial herb native to the Northern hemisphere and found growing wild in meadows, pastures, and waste grounds of temperate zones. Most commercial dandelion is cultivated in Bulgaria, Hungary, Poland, Romania, and the United Kingdom.

Dandelion was commonly used in Native American medicine. The Iroquois, Ojibwe, and Rappahannock prepared the root and herb to treat kidney disease, upset stomach, and heartburn. In traditional Arabian medicine, dandelion has been used to treat liver and spleen ailments. In traditional Chinese medicine (TCM), dandelion is combined with other herbs to treat liver disease, to enhance immune response to upper respiratory tract infections, bronchitis, or pneumonia, and as a compress for mastitis (breast inflammation).

Dandelion root and leaf are used widely in Europe for gastrointestinal ailments. The European Scientific Cooperative on Phytotherapy (ESCOP) recommends dandelion root for the restoration of liver function, to treat upset stomach, and to treat loss of appetite. The German Commission E authorizes the use of combination products containing dandelion root and herb for similar illnesses. Some modern naturopathic physicians assert that dandelion can detoxify the liver and gallbladder, reduce side effects of medications metabolized (processed) by the liver, and relieve symptoms associated with liver disease.

Dandelion is generally regarded as safe with rare side effects including contact dermatitis, diarrhea, and gastrointestinal upset.

Dandelion is used as a salad ingredient, and the roasted root and its extracts are sometimes used as a coffee substitute.

Evidence

DISCLAIMER:
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Anti-inflammatory:
Research in laboratory animals suggests that dandelion root may possess anti-inflammatory properties. There is a lack of well-conducted human studies currently available in this area.
Grade: C

Antioxidant:
Several laboratory studies report antioxidant properties of dandelion flower extract, although this research is preliminary, and effects in humans are not known.
Grade: C

Cancer:
Limited animal research does not provide a clear assessment of the effects of dandelion on tumor growth. There is a lack of well-conducted human studies currently available in this area.
Grade: C

Colitis:
There is a report with several patients that suggests that a combination herbal preparation containing dandelion improved chronic pain associated with colitis. Because multiple herbs were used, and this study was not well-designed or reported, the effects of dandelion are not clear.
Grade: C

Diabetes:
There is limited research on the effects of dandelion on blood sugar levels in animals. Effects in humans are not known.
Grade: C

Diuretic (increased urine flow):
Dandelion leaves have traditionally been used to increase urine production and excretion. Animal studies report mixed results, and there is a lack of reliable human research in this area.
Grade: C

Dosing

Adults (18 years and older)

There is no proven effective dose for dandelion in adults. However, doses of 2-8 grams of dried root taken by mouth in an infusion or decoction have been used.

Doses of 4-8 milliliters of a 1:1 leaf fluid extract in 25 percent alcohol have been used.

Doses of 1-2 teaspoons of a 1:5 root tincture in 45 percent alcohol have been used.

Children (younger than 18 years)

There is not enough scientific research to recommend dandelion for use in children in amounts greater than those found in food.

Safety

DISCLAIMER:
Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Allergies

Dandelion should be avoided by individuals with known allergy to honey, chamomile, chrysanthemums, yarrow, feverfew, or any members of the Asteraceae/Compositae plant families (ragweed, sunflower, daisies).

The most common type of allergy is dermatitis (skin inflammation) after direct skin contact with dandelion, which may include itching, rash, or red/swollen or eczematous areas on the skin. Skin reactions have also been reported in dogs.

Rhinoconjunctivitis and asthma have been reported after handling products, such as birdfeed, containing dandelion and other herbs with reported positive skin tests for dandelion hypersensitivity.

Side Effects and Warnings

Dandelion has been well tolerated in a small number of available human studies. Safety of use beyond four months has not been evaluated.

The most common reported adverse effects are skin allergy, eczema, and increased sun sensitivity following direct contact.

According to traditional accounts, gastrointestinal symptoms may occur, including stomach discomfort, diarrhea, and heartburn.

Parasitic infection due to ingestion of contaminated dandelion has been reported, affecting the liver and bile ducts, and characterized by fever, stomach upset, vomiting, loss of appetite, coughing, and liver damage.

Dandelion may lower blood sugar levels based on one animal study, although another study notes no changes. Effects in humans are not known. Caution is advised in patients with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare professional, and medication adjustments may be necessary.

Dandelion may be prepared as a tincture containing high levels of alcohol. Tinctures should therefore be avoided during pregnancy or when driving or operating heavy machinery.

Pregnancy and Breastfeeding

Dandelion cannot be recommended during pregnancy and breastfeeding in amounts greater than found in foods, due to a lack of scientific information. Many tinctures contain high levels of alcohol and should be avoided during pregnancy.

Interactions

Interactions with Drugs

Drug interactions with dandelion have rarely been identified, although there is limited study in this area.

Dandelion may reduce the effects of the antibiotic ciprofloxacin (Cipro®) due to reduced absorption of the drug. In theory, dandelion may reduce the absorption of other drugs taken at the same time.

Dandelion may lower blood sugar levels, although another study notes no changes. Although effects in humans are not known, caution is advised in patients taking prescription drugs that may also lower blood sugar levels. Those using oral drugs for diabetes or insulin should be monitored closely by a healthcare professional while using dandelion. Dosing adjustments may be necessary.

Historically, dandelion is believed to possess diuretic (increased urination) properties and to lower blood potassium levels. In theory, the effects or side effects of other drugs may be increased, including other diuretics, lithium, digoxin (Lanoxin®), or corticosteroids such as prednisone. However, dandelion also contains potassium and human supportive evidence is lacking.

The effects or side effects of niacin or nicotinic acid may be increased (such as flushing and gastrointestinal upset), due to small amounts of nicotinic acid present in dandelion.

In theory, due to chemicals called coumarins found in dandelion leaf extracts, dandelion may increase the risk of bleeding when used with blood thinners. Examples include warfarin (Coumadin®), heparin, and clopidogrel (Plavix®). Some pain relievers may also increase the risk of bleeding if used with dandelion. Examples include aspirin, ibuprofen (Motrin®, Advil®), and naproxen (Naprosyn®, Aleve®, Anaprox®). It is possible that dandelion may reduce the effectiveness of antacids or drugs commonly used to treat peptic ulcer disease. Examples include famotidine (Pepcid®) and esomeprazole (Nexium®).

Dandelion may interfere with the way the liver breaks down certain drugs (using the P450 1A2 and 2E enzyme systems). As a result, the levels of these drugs may be raised in the blood, and the intended effects or side effects may be increased. Patients using medications should check the package insert and speak with a healthcare professional, including a pharmacist, about possible interactions.

Be aware that many tinctures contain high levels of alcohol and may cause nausea or vomiting when taken with metronidazole (Flagyl®) or disulfiram (Antabuse®).

Although not well studied in humans, caution is advised in patients taking analgesics (pain-relievers), anesthetics, anti-inflammatories, or certain types of antacids or peptic ulcer agents (Pepcid® or Nexium®). Dandelion may increase the effects and toxicity of blood pressure-lowering agents or niacin if taken together.

Dandelion may also interact with cholesterol-lowering agents, such as bile acid sequestrants. Consult with a qualified healthcare professional, including a pharmacist, to check for interactions.

Other potential interactions with dandelion that are lacking human scientific evidence include anticancer agents, appetite suppressants, hormonal agents (such as estrogens), laxatives, and agents used to treat gout.

Interactions with Herbs and Dietary Supplements

Interactions of dietary supplements with dandelion have rarely been published, although there is limited study in this area.

Based on an animal study, dandelion may lower blood sugar levels, although another study notes no changes. Although effects in humans are not known, caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Historically, dandelion is believed to possess diuretic (increased urination) properties and may increase the effects of other herbs with potential diuretic effects, such as artichoke, elder flower, or horsetail.

In theory, due to chemicals called coumarins found in dandelion leaf extracts, dandelion may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Dandelion may interfere with the way the liver breaks down certain drugs (using the P450 1A2 and 2E enzyme systems). As a result, the levels of other herbs or supplements may become too high in the blood. In theory, dandelion may also alter the effects that other herbs or supplements possibly have on the P450 system, such as bloodroot, grapefruit juice, or St. John's wort.

Dandelion leaves contain vitamin A, niacin, lutein, and beta-carotene and thus, supplemental doses of these agents may have additive effects or side effects.

Dandelion may reduce the effectiveness of the antibiotic ciprofloxacin (Cipro®) and thus may have interactions with other antibacterial herbs or supplements.

Although not well studied in humans, dandelion may interact with anti-inflammatory agents, antacids, analgesics, hormone replacement therapy (HRT), laxatives, nondigestible oligosaccharides (such as inulin), urine alkalinizing herbs and supplements, anticancer herbs or supplements, or other antioxidants. Dandelion may also decrease dehydroepiandrosterone, dehydroepiandrosterone-sulfate, androstenedione, and estrone-sulfate levels.

Dandelion may increase the toxic effects when taken with supplements that lower blood pressure such as hawthorn (Crataegus laevigata). Toxic effects associated with herbs such as foxglove may increase when used in combination with dandelion.